/**
 * Copyright (c) 2005-2010 springside.org.cn
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * 
 * $Id: Struts2Utils.java 1211 2010-09-10 16:20:45Z calvinxiu $
 */
package cn.newtouch.util;

import java.io.IOException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.commons.lang.StringUtils;
import org.apache.struts2.ServletActionContext;
import org.codehaus.jackson.map.ObjectMapper;

/**
 * Struts2工具类.
 * 
 * 实现获取Request/Response/Session与绕过jsp/freemaker直接输出文本的简化函数.
 * 
 * @author calvin
 */
public class Struts2Utils
{

    // -- header 常量定义 --//
    private static final String  HEADER_ENCODING  = "encoding";

    private static final String  HEADER_NOCACHE   = "no-cache";

    private static final String  DEFAULT_ENCODING = "UTF-8";

    private static final boolean DEFAULT_NOCACHE  = true;

    private static ObjectMapper  mapper           = new ObjectMapper();

    // -- 取得Request/Response/Session的简化函数 --//
    /**
     * 取得HttpSession的简化函数.
     */
    public static HttpSession getSession()
    {
        return ServletActionContext.getRequest().getSession();
    }

    /**
     * 取得HttpSession的简化函数.
     */
    public static HttpSession getSession(boolean isNew)
    {
        return ServletActionContext.getRequest().getSession(isNew);
    }

    /**
     * 取得HttpSession中Attribute的简化函数.
     */
    public static Object getSessionAttribute(String name)
    {
        HttpSession session = getSession(false);
        return (session != null ? session.getAttribute(name) : null);
    }

    /**
     * 取得HttpRequest的简化函数.
     */
    public static HttpServletRequest getRequest()
    {
        return ServletActionContext.getRequest();
    }

    /**
     * 取得HttpRequest中Parameter的简化方法.
     */
    public static String getParameter(String name)
    {
        return getRequest().getParameter(name);
    }

    /**
     * 取得HttpResponse的简化函数.
     */
    public static HttpServletResponse getResponse()
    {
        return ServletActionContext.getResponse();
    }

    // -- 绕过jsp/freemaker直接输出文本的函数 --//
    /**
     * 直接输出内容的简便函数.
     * 
     * eg. render("text/plain", "hello", "encoding:GBK"); render("text/plain",
     * "hello", "no-cache:false"); render("text/plain", "hello", "encoding:GBK",
     * "no-cache:false");
     * 
     * @param headers
     *            可变的header数组，目前接受的值为"encoding:"或"no-cache:",默认值分别为UTF-8和true.
     */
    public static void render(final String contentType, final String content,
            final String... headers)
    {
        HttpServletResponse response = initResponseHeader(contentType, headers);
        try
        {
            response.getWriter().write(content);
            response.getWriter().flush();
        }
        catch (IOException e)
        {
            throw new RuntimeException(e.getMessage(), e);
        }
    }

    /**
     * 直接输出文本.
     * 
     * @see #render(String, String, String...)
     */
    public static void renderText(final String text, final String... headers)
    {
        render(ServletUtils.TEXT_TYPE, text, headers);
    }

    /**
     * 直接输出HTML.
     * 
     * @see #render(String, String, String...)
     */
    public static void renderHtml(final String html, final String... headers)
    {
        render(ServletUtils.HTML_TYPE, html, headers);
    }

    /**
     * 直接输出XML.
     * 
     * @see #render(String, String, String...)
     */
    public static void renderXml(final String xml, final String... headers)
    {
        render(ServletUtils.XML_TYPE, xml, headers);
    }

    /**
     * 直接输出JSON.
     * 
     * @param jsonString
     *            json字符串.
     * @see #render(String, String, String...)
     */
    public static void renderJson(final String jsonString,
            final String... headers)
    {
        render(ServletUtils.JSON_TYPE, jsonString, headers);
    }

    /**
     * 直接输出JSON,使用Jackson转换Java对象.
     * 
     * @param data
     *            可以是List<POJO>, POJO[], POJO, 也可以Map名值对.
     * @see #render(String, String, String...)
     */
    public static void renderJson(final Object data, final String... headers)
    {
        HttpServletResponse response = initResponseHeader(
                ServletUtils.JSON_TYPE, headers);
        try
        {
            mapper.writeValue(response.getWriter(), data);
        }
        catch (IOException e)
        {
            throw new IllegalArgumentException(e);
        }
    }

    /**
     * 直接输出支持跨域Mashup的JSONP.
     * 
     * @param callbackName
     *            callback函数名.
     * @param object
     *            Java对象,可以是List<POJO>, POJO[], POJO ,也可以Map名值对, 将被转化为json字符串.
     */
    public static void renderJsonp(final String callbackName,
            final Object object, final String... headers)
    {
        String jsonString = null;
        try
        {
            jsonString = mapper.writeValueAsString(object);
        }
        catch (IOException e)
        {
            throw new IllegalArgumentException(e);
        }

        String result = new StringBuilder().append(callbackName).append("(")
                .append(jsonString).append(");").toString();

        // 渲染Content-Type为javascript的返回内容,输出结果为javascript语句,
        // 如callback197("{html:'Hello World!!!'}");
        render(ServletUtils.JS_TYPE, result, headers);
    }

    /**
     * 分析并设置contentType与headers.
     */
    private static HttpServletResponse initResponseHeader(
            final String contentType, final String... headers)
    {
        // 分析headers参数
        String encoding = DEFAULT_ENCODING;
        boolean noCache = DEFAULT_NOCACHE;
        for (String header : headers)
        {
            String headerName = StringUtils.substringBefore(header, ":");
            String headerValue = StringUtils.substringAfter(header, ":");

            if (StringUtils.equalsIgnoreCase(headerName, HEADER_ENCODING))
            {
                encoding = headerValue;
            }
            else
                if (StringUtils.equalsIgnoreCase(headerName, HEADER_NOCACHE))
                {
                    noCache = Boolean.parseBoolean(headerValue);
                }
                else
                {
                    throw new IllegalArgumentException(headerName
                            + "不是一个合法的header类型");
                }
        }

        HttpServletResponse response = ServletActionContext.getResponse();

        // 设置headers参数
        String fullContentType = contentType + ";charset=" + encoding;
        response.setContentType(fullContentType);
        if (noCache)
        {
            ServletUtils.setDisableCacheHeader(response);
        }

        return response;
    }

}
